Through bolt commutator



Jan. 17, 1950 w. WRIGHT 2,495,194

THROUGH 1301:; COMMUTATOR Filed Oct. 13, 1948 WITNESSES: INVENTOR W M Willard L. Wright.

ATTORNEY Patented Jan. 17, 1950 THROUGH BOLT COMZMUTATOR Willard L. Wright, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 13, 1948, Serial No. 54,296

2 Claims.

My invention relates to commutator-type dynamo-electric machines, and it has particular relation to the means for holding the commutators of such machines in assembled position. My invention was particularly designed for a railway-type traction-motor, but its general principles are applicable to other types of dynamo-electric machines.

The principal object of my invention is to provide a construction of a commutator in which the assembly-bolts extend through the armaturecore as well as through the commutator, thereby providing a construction which combines flexibility of compression of the commutator-assembly, with low cost, while at the same time reducing the commutator-length, the overall motorlength, and the size of the front steel V-ring of the commutator, while making it possible to assemble the commutator by using a torquewrench without requiring a pressing machine.

With the foregoing and other objects in View, my invention relates to the assemblies, structures, combinations, parts and methods of manufacture and use, hereinafter described and claimed, and illustrated in the accompanying drawing, Wherein the single figure is a fragmentary longitudinal sectional view of an exemplary form of motor embodying my invention.

As shown in the drawing, the invention is embodied in a dynamo-electric machine comprising a rotatable shaft I, an armature-core 2 carried by said shaft, and an armature-winding 3 carried by said armature-core. The machine also has a field-member 4 which is carried by a motorframe 5 which has end-brackets 6 carrying the bearings l for supporting the shaft I.

Inside the machine, on the shaft I in front of the armature-core 2, is a cylindrical-surfaced commutator-member 8, comprising segmental commutator-bars which are connected, at their rear ends, tothe coil-terminals of the armaturewinding 3, as indicated at 9. Each commutatorbar has front and rear V-grooves II and I2 therein, which are mounted, in a common manher, on front and rear V-rings I3 and I I, respectively, which are usually made of steel and insulated from the V-grooves by insulation I5.

My invention relates to the method and means for holding the two V-rings I3 and I4 in assembled relation on the shaft I, while exerting a yieldable axial pressure tending to draw the two V-rings together so as to support the assembled commutator bars 8. The rear V-ring I4 may be of conventional construction. It is abutment against a shoulder-means I6 which is carried by the shaft. The front V-ring I3, in the illustrated form of embodiment of my invention, is special, being smaller in size than has usually been required heretofore, having a smooth inclined front surface H which has no projections thereon, and which provides good clearance for the front-end bearing-mounting 1, thereby reducing the overall length of the machine. The front V-ring I3 has an inner bore or periphery I8 which is closer to the commutator 8, or further away from the shaft I, than has usually been possible in constructions which have used the successful disk-spring commutatordesign which is covered by the Moore Patent 1,826,628, granted October 6, 1931.

According to my invention, the assemblymeans for drawing the front V-ring l3 axially toward the rear V-ring I l consists of a plurality of assembly-bolts or studs 20, which extend from a shoulder-means 2i which is carried by the shaft I at the rear of the armature-core 2, to engage tapped holes 22 which are drilled in the rear of the front V-ring I3. The central-bolt portions, which are not threaded, are necked down so as to have the same or smaller mechanical strength than the threaded terminal portions of the bolts, thereby providing a maximum resiliency, these necked-down bolt-portions extending all the way through the armaturemember 2, and through holes 25 which are provided therefor in the rear V-ring I4.

It will be noted that the space between my rear V-ring I l and the armature-member 2 may be shorter, axially, than heretofore, because of the absence of any bolt-heads or any disk-spring at either the front or rear end of the commutator 8. It will also be noted that the absence of the disk-spring construction makes it possible to move the bolts 20 radially outwardly, closer to the commutator-assembly 8, thus relieving strains on the front V-ring I3 and making it possible to use a smaller front V-ring construction than has frequently been possible heretofore.

I have not undertaken to show any particular ventilating-means for the motor which I have illustrated, as any desired ventilating-means may be used with my invention.

In the operation of my invention, it will be noted that the commutator-assembly bolts 20 are provided with bolt-heads or nuts 26 which are accessible from the rear end of the machine, the front surfaces of these bolt-heads or nuts abutting against the rear-end abutment-shoulder 2|. Be-

assembled on the shaft I with its rear edge in cause of the long bolt-length which is thus provided, the bolts 20 are quite resilient, and the commutator V-rings l3 and M can be drawn together by the use of a torque-measuring wrench (not shown), applied to the bolt-heads o-r nuts 26 at the rear end of the machine, without requiring the use of a hydraulic pressure-machine for holding the commutator V-rings together during the assembly-operation. The long length of the through-bolts 20 also provides an excellent fo-llow-up movement, so as to yieldably hold the commutator-assembly together without requiring the use of a disk-spring such as is disclosed in the aforesaid Moore patent, thus saving the cost and the space previously required by such a disk-spring, as Well as providing the other advantages which have been named.

While I have shown my invention in but a single illustrative form of embodiment, I Wish it to be understood that my invention is not limited to the particular details which have been illustrated. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A dynamo-electric machine comprising a rotatable shaft, an armature-core carried by said shaft, an armature-Winding carried by said armature-core, and a cylindrical-surfaced com mutator-member carried by said shaft in front of said armature-core, said commutator-member comprising segmental commutator-bars connected at their rear ends to said armature-winding, each commutator-bar having a front vgroove and a rear V-groove therein, a front V-ring and a rear V-ring disposed in positions to enter the front and rear V-grooves, respectively, of the assembled commutator-bars, an intermediate shoulder-means carried by the shaft for forming an abutment for the rear end of the rear V-ring, a rear-end shoulder-means carried by the shaft tothe rear of the armature-core, and a plurality of through-bolts extending axially between the rear-end shoulder-means and the front l-r ing for clamping said V-rings in commutator-holding position.

2. The invention as defined in claim 1, characterized by said through-bolts having heads engaging the rear of said rear-end shoulder-means, and having threaded front ends engaging threaded holes in the front V-ring.

WILLARD L. WRIGHT.

No references cited. 

